Vehicle engines commonly utilize cooling assemblies to remove excess heat from the engine and maintain an optimal operating temperature. The cooling assembly pumps a coolant through the engine and other components in order to control engine temperature. Heat generated within the engine and other components is absorbed by the coolant and dispersed into the surrounding atmosphere through the use of a radiator. In order to improve dispersal by the radiator, it is common to utilize fan assemblies to draw or force air past the radiator to assist in temperature transmission.
It is not always desirable for such fan assemblies to be run continuously. At times, it is desirable for the temperature within the coolant to increase rather than decrease. Additionally, continuous operation when unnecessary places a non-required draw on the engine and thereby reduces efficiency. To compensate for this, present fan assemblies utilize fan clutch assemblies that allow for the selective engagement of the fan to the engine such that the fans are engaged only when necessary.
The present invention relates to friction coupling devices that drive radiator-cooling fans. A common friction-coupling device is that of the dry friction drive style, otherwise referred to interchangeably hereinafter with a friction clutch assembly. Dry friction drives are used for their simplicity, cool operating temperature, and ability to turn at fully engaged peak operating speeds.
Although the present invention may be used advantageously in various configurations and applications, it is especially advantageous in a coupling device of the type used to drive a radiator cooling fan of an internal combustion engine for an over-the-road truck, such as a class 8 truck, and will be described in connection therewith.
Dry friction drives tend to have two operating conditions “ON and OFF”, which refers to when an associated friction clutch is either fully engaged or fully disengaged. When a friction clutch assembly is fully engaged, the assembly provides cooling to an associated engine and is not slipping. When a friction clutch assembly is fully disengaged slippage between the clutch plate and an engagement surface is at a maximum, thus providing little rotational output to drive an associated fan.
In order to engage the fan drive, a friction liner is typically mounted between the clutch housing and rotating driveshaft utilizing a series of stamped plates and screws. These plates and screws add to the overall cost of the clutch systems both in terms of part count and in terms of manufacturing assembly steps.
It would therefore be highly desirable to find a more cost effective method for axial retaining the friction liner between the clutch housing and rotating shaft.